This invention relates generally to the field of photolithography and more specifically to a trim mask for an alternating phase-shift exposure system.
A photolithography mask may be used to pattern an object such as a semiconductor wafer of an integrated circuit. The mask may be positioned between a light source and the object. Light from the light source is selectively transmitted, blocked, or otherwise affected by the mask to define a pattern on the object. A mask such as an embedded attenuated phase-shift mask includes attenuated phase-shift regions. An attenuated phase-shift region transmits a small percentage of light and shifts the phase of transmitted light. Light passing through an attenuated phase-shift region may destructively interfere with light passing through an adjacent transparent region, which may allow for higher resolution pattern definition in certain situations. Embedded attenuated phase-shift masks, however, do not provide for high resolution pattern definition in other situations. It is generally desirable to have high resolution pattern definition in a variety of situations.